Abstract 514: Cardiac Sympathetic Denervation Assessed With 123-Iodine Metaiodobenzylguanidine Imaging Predicts Ventricular Arrhythmias in Patients With Implantable Cardioverter-Defibrillator
Objectives A large number of patients with implantable cardioverter-defibrillator (ICD) therapy does not receive appropriate ICD therapy for ventricular arrhythmias. Although sympathetic nerve dysfunction, assessed with 123-iodine metaiodobenzylguanidine (123-I MIBG) imaging, has been associated with ventricular arrhythmias, the role of 123-I MIBG imaging for prediction of ventricular arrhythmias is unknown. Accordingly, this study evaluated the role of 123-I MIBG imaging for prediction of appropriate ICD therapy (primary endpoint) as well as the composite of appropriate ICD therapy or cardiac death (secondary endpoint).
Methods One-hundred sixteen consecutive heart failure patients referred for ICD therapy were included. Patients underwent 123-I MIBG (early and late) and myocardial perfusion (rest and stress) imaging before ICD implantation. During clinical follow-up, appropriate ICD therapy and cardiac death were documented. Imaging variables were related to the occurrence of endpoints.
Results During a mean follow-up of 25±15 months, appropriate ICD therapy was documented in 24 (21%) patients and appropriate ICD therapy or cardiac death in 32 (28%) patients. Late 123-I MIBG SPECT defect score and secondary ICD indication were independent predictors for appropriate ICD therapy. Late 123-I MIBG SPECT defect score was the only independent predictor for appropriate ICD therapy or cardiac death. Patients with high late 123-I MIBG SPECT defect score (>26) showed significantly more appropriate ICD therapy (79% vs. 5%, p<0.01) and appropriate ICD therapy or cardiac death (83% vs. 10%, p<0.01) as compared to patients with low late 123-I MIBG SPECT defect score (≤26) after 4-year follow-up.
Conclusion Cardiac sympathetic denervation on late 123-I MIBG imaging predicts appropriate ICD therapy and the composite of appropriate ICD therapy or cardiac death in patients meeting current selection criteria for ICD therapy. Cardiac sympathetic denervation, as assessed with 123-I MIBG imaging, allows identification of patients who will benefit from ICD therapy. 123-I MIBG imaging may enable improved risk stratification for cardiac death in patients currently indicated for ICD treatment.